1. Field of the Invention
The present invention relates to a projection optical system and a projector apparatus.
2. Description of the Related Art
Recently, there has been widely used an image display device that generates an image with a digital mirror device (DMD) or a liquid crystal panel and projects it on a screen. Particularly, there is an increasing demand for a front projection type projector having an ultra-short projection distance that achieves a large screen with a short projection distance. Moreover, in addition to an ultra-short projection distance, the downsizing of an apparatus is demanded.
The projection optical system disclosed in Japanese Patent Application Laid-open No. 2008-250296 forms an intermediate image with a refractive optical system and performs enlarged projection thereof using a concave surface mirror. Thus, it is possible to downsize the apparatus by reducing the size of the mirror and achieve an ultra-short projection distance.
In the projection optical system disclosed in Japanese Patent Application Laid-open No. 2008-250296, a size of an intermediate image is not optimized, and thus the mirror is not sufficiently reduced in size. Moreover, in the projection optical system disclosed in Japanese Patent Application Laid-open No. 2008-250296, the projection distance is not sufficiently short. Furthermore, the projection optical system disclosed in Japanese Patent Application Laid-open No. 2008-250296 has a problem that the size of a housing is increased because the mirror is not sufficiently reduced in size.
In view of the above aspects, there is a need to provide a small-sized high-performance projection optical system and a projector apparatus.